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Which is the main chemical element present in coal and petroleum?

Carbon is the basic chemical element present in fossil fuels.... View Article

The penetration of light into the region of geometricalshadow is called

It is caused due to turning of light around corners.... View Article

If a force is exerted on an object, it will definetely cause motion in the body.

This statement is wrong. Force may or may not cause motion. If all the forces acting on a body are not balanced, then the body moves.... View Article

What are the unequal and opposite forces acting on a body, which change its state of rest or uniform motion called?

Unequal and opposite forces acting on a body, which change its state of rest or uniform motion are called unbalanced forces.... View Article

Which of the following statements is/are true? 1. Forces in same direction will be added. 2. Two forces in opposite direction result in a net force equal to their difference in the direction of larger force. 3. Change in either direction or magnitude of force changes its effect. 4. When more than one forces are acting on it, effect on the object is due to net force acting on it.

When you and your friend push a box in the same direction, it is easier to push the box because the force applied by both of you adds to give the... View Article

In watershed management which of the following is a primary resource?

Land and water are the primary resources in watershed management.... View Article

One end of a cart is tied to a horse and the other end to another horse, both the horse trying to move cart in their respective directions. It was observed that the cart was at rest, this is because

As the cart continued to be at rest after the application of force by the horses at the opposite ends, which means that the horses were applying... View Article

Two loudspeakers L1 and L2 driven by a common oscillator and amplifier, are arranged. The frequency of the oscillator is gradually increased from zero and the detector at D records a series of maxima and minima. If the speed of sound is 330 ms-1, then the frequency at which the first maximum is observed is

Path difference Δx=√92+402−40=1 m Hence, phase change = δ = 2π/λ Δx = 2π/λ For the first maximum δ=2π/λ =2π Hence, λ=1 m Frequency=ν=v/λ =330 Hz... View Article

Net force acting on a body is zero, if two forces acting on it are

When two forces acting on a body are in opposite direction, the net force is the difference between two forces in the direction of larger force.... View Article

What happens when current is passed in an antimony-bismuth couple? (1) The junction becomes hot when current flows from antimony to bismuth (2) The junction becomes hot when the current flows from bismuth to antimony (3) Both junctions become hot (4) Both junctions become cold.

Answer: (2) The junction becomes hot when the current flows from bismuth to antimony In 1834, Peltier discovered that when an electric current... View Article

How many 176W resistors (in parallel) are required to carry 5 A in 220 V line?

Here, I = 5A, V = 220 V.Resistance required in the circuit, R = V/I = 220V/5A = 44 W, Resistance of each resistor, r = 176 WIf n resistors, each... View Article

Aray of light is incident on the surface of a glass plate at an angle of incidence equal to Brewster’s anglerepresents the refractive index of glass with respect to air, then the angle between reflected and refracted rays is[CPMT 1989]

At polarizing angle, the reflected and refracted rays are mutually perpendicular to each other.... View Article

Water is cooled from 4oC to 0oC. It will :

When water is cooled from 4oC to 0oC, it will expand due to its anomalous behaviour.... View Article

The following disintegration reactions are i) zXA → Z -2Y A + α ii) zXA → Z -1PA + β

Not correct as mass number should have reduced by 4 and not remained the same on Alpha emissionNot correct as the atomic number should have... View Article

Which of the Millikan’s method is used for the determination of charge?

Millikan oil-drop experiment is used for determining the electron charge of an electron. It was first performed by the Robert A Millikan, an... View Article

Observation 1: Try to stop a ball coming towards you,so as to save a boundary, by applying a force of some magnitude in the opposite direction of the motion of ball. Observation 2: In this case apply the force of same magnitude but in same direction of the motion of the ball. In observation 1 boy saves a boundary by applying a force opposite to the direction of motion but in observation 2, the change in direction of force cost the team 4 runs as the change in direction of force pushed the ball further to the boundary. So, the change in effect of a force can be experienced by a change in it’s direction as well as magnitude. The above statement is :-

In the above two observations it is clear that the change in direction of force in the second observation made the team cost four runs. So,... View Article

A ray of light moves from a rare medium to a dense medium as shown in the diagram below. The ray or rays which represents the partially reflected ray is:

Ray 1 is incident ray, ray 3 is the refracted ray and ray 2 is the partially reflected ray.... View Article

M	T	W	T	F	S	S
				1	2	3
4	5	6	7	8	9	10
11	12	13	14	15	16	17
18	19	20	21	22	23	24
25	26	27	28	29	30